Polypectomy snare instrument

ABSTRACT

A medical device and methods for making and using the same. An example medical device includes a tubular member, a shaft disposed within the tubular member, and an end effector coupled to the shaft. A first handle and a second handle may be coupled to the shaft. A tubular sheath extension may be disposed between the first handle and the second handle.

CROSS REFERENCE TO CO-PENDING APPLICATIONS

This application is a continuation of co-pending U.S. application Ser.No. 09/854,812, filed May 14, 2001; which is a continuation ofco-pending U.S. patent application Ser. No. 09/369,724, filed Aug. 6,1999, now U.S. Pat. No. 6,235,026, the disclosures of which are allhereby incorporated by reference.

FIELD OF THE INVENTION

This invention relates broadly to surgical instruments. Moreparticularly, this invention relates to a surgical snare instrument forexcising polyps.

BACKGROUND OF THE INVENTION

Polypectomy snare instruments are used for the endoscopic removal ofhypertrophic tissue growths within a body cavity, and particularlywithin the colon. Polypectomy snare instruments generally include anelongate tubular member, such as a catheter sheath, a shaft extendingthrough the tubular member, an elastic wire forming a snare (loop) atthe distal end of the shaft, and a handle for moving the shaft distallyand proximally within the tubular member. The snare can be opened bymoving the snare beyond the distal end of the sheath and closed byretraction of the snare into the tubular member, each effected bymovement of the shaft relative to the sheath.

In operation, a physician introduces the distal end of the instrument,with the snare of the snare instrument in a retracted position, throughthe working channel of an endoscope until the sheath begins to extendout of the distal end of the endoscope. The physician then directs anassistant, who has control of the handle of the snare instrument, toopen the snare. The assistant accomplishes this function by moving twoportions of the handle relative to each other. The physician thenadvances and retracts the sheath into and out of the endoscope, whileapplying torque to some portion of the instrument to position the snareloop over and around a polyp. Once the snare loop is positioned aroundthe polyp, the physician orders the assistant to close the snare aroundthe polyp. Then, the physician or assistant energizes a source ofelectrocautery current coupled to the shaft to desiccate, sever, andcauterized the polyp. Finally, the polyp is removed by withdrawing thesnare (or, in some cases, the polyp is retrieved by use of anotherinstrument such as a biopsy forceps). In a variation of the procedure,the physician uses suction applied to a channel of the endoscope toremove the polyp or to hold it to the end of the endoscope.

Prior art snare instruments have several problems. First, it isdifficult for the physician to precisely position the snare because thephysician relies on gripping the small, slippery sheath over the shaftnear where the sheath enters the endoscope handle. Typically, it isnecessary for the physician to repeatedly push, pull, and torque thesheath and the shaft of the instrument in order to achieve the desiredposition with the snare around the polyp. Second, the prior artinstruments are not capable of efficient steering, because the shaftwhich is generally used is a cable having low torsional stiffness, andis not usually free of camber or “set”. The result of these defects isthat when the instrument is used in a tightly-flexed endoscope, thedistal end of the snare does not respond directly to torsional input onthe shaft where it enters the endoscope handle; i.e., rather thandirectly respond to torsional input from the physician, the shaft storesthe torsional force and upon reaching a threshold, uncontrollablerotationally whips to release the force. Third, while several attemptshave been made at providing a snare instrument with a handle adapted tomore adeptly steer the snare, most of such prior art instruments do notspecifically allow for rotating the snare to position it relative to thepolyp. Rather, the physician must rotate the shaft of the instrument bytightly gripping and rotating the sheath where it enters the endoscopeto try to maneuver the snare over the polyp. In addition, in the severalprior art devices specifically adapted for rotational control, e.g.,U.S. Patent No. 5,066,295 to Kozak et al. and U.S. Pat. Nos. 3,955,587,4,256,113, and 4,294,254 to Chamness et al., the rotational controlfunction is placed in the handle at the proximal end of the instrument.This handle then controls the extension and retraction of the snare loopas well as the rotation of the snare loop. However, this handle istypically held by the assistant, so the physician must orally direct theassistant to coordinate the handle controls while the physician movesthe jacket in and out of the endoscope. As a result, these instrumentshave not been widely accepted by physicians.

SUMMARY OF THE INVENTION

It is therefore an object of the invention to provide a snare instrumentwhich permits the physician to control all aspects of positioning thesnare loop relative to the polyp, while allowing the assistant toperform the cauterizing and severing of the polyp.

It is a further object of the invention to provide a snare instrumentwhich provides to the physician the means for advancing and retractingthe distal end of the snare instrument through the endoscope, as well asrotating the snare, and which provides to the assistant the means forextending and retracting the snare loop from the sheath of the snareinstrument.

It is another object of the invention to provide a snare instrument inwhich the physician has direct and immediate control of the entireinstrument.

It is also an object of the invention to provide a snare instrumentwhich obviates the need for an assistant during a polypectomy procedure.

It is yet another object of the invention to provide a snare instrumentwhich improves the speed and efficiency of a polypectomy procedure.

In accord with these objects, which will be discussed in detail below, asurgical snare instrument is provided. The snare instrument includes anelongate flexible tubular sheath, a flexible shaft extending through andaxially movable relative to the sheath, a snare coupled to or formed atthe distal end of the shaft, and a system to move the shaft, andconsequently the snare, relative to the sheath. According to severalembodiments of the invention, the system for moving the shaft relativeto the sheath includes a first (physician's) handle capable ofcontrolling the position of the snare, and a second (assistant's) handleproximal the first handle and adapted to control contraction of thesnare and cauterization. The handles are coupled by a tubular sheathextension.

The physician's handle is preferably positioned along the sheath of thesnare instrument so that it is a few inches proximal to the entry portof the endoscope handle when the distal end of the sheath is adjacent tothe distal end of an endoscope. The physician's handle serves as agrippable element on the sheath and contains a rotating means forrotating the shaft, so that when the physician grips that handle thephysician is capable of steering (rotating) the snare by operating therotating means. In addition, the physician is also capable ofpositioning the entire sheath relative to the endoscope by sliding thesheath into and out of the working channel of the endoscope. Theproximal handle is operable by an assistant and permits longitudinalmovement of the shaft and snare and the application of a cautery currentto the shaft and snare.

According to other embodiments, the snare instrument is provided with aconnector which enables the snare instrument to be fixed relative to anendoscope handle. Additionally, an embodiment is also provided in whicha single handle provides a physician with means for advancing andretracting the sheath of the snare instrument relative to the distal endof the endoscope, means for advancing (opening) and retracting (closing)the snare relative to the distal end of the sheath, and means forsteering (rotating) the snare to position the snare over a polyp. Sincethe physician has direct and immediate control of the entire instrument,the snare instrument obviates the need for an assistant during theprocedure, and improves the speed and efficiency of the polypectomyprocedure.

Additional objects and advantages of the invention will become apparentto those skilled in the art upon reference to the detailed descriptiontaken in conjunction with the provided figures.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is broken side elevation in section of a first embodiment of asnare instrument according to the invention;

FIG. 2 is an enlarged cross-section taken through line 2-2 in FIG. 1;

FIG. 3 is an enlarged cross-section taken through line 3-3 in FIG. 1;

FIG. 4 is an enlarged cross-section taken through line 4-4 in FIG. 1;

FIG. 5 is a broken section view of a physician's handle assemblyaccording to the second embodiment of the snare instrument of theinvention;

FIG. 6 is an enlarged cross-section through line 6-6 in FIG. 5, showingthe engagement of a key in a knob shaft;

FIG. 7 is an enlarged cross-section through line 7-7 in FIG. 5, at alocation proximal of the key;

FIG. 8 is a broken section view of a third embodiment of the snareinstrument according to the invention;

FIG. 9 is an enlargement of the area between lines 9 a-9 a and 9 b-9 bin FIG. 8.

FIG. 10 is a broken section view of a fourth embodiment of the snareinstrument of the invention; and

FIG. 11 is a broken section view of a fifth embodiment of the snareinstrument of the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Turning now to FIG. 1, a first embodiment of a surgical snare instrument10 according to the invention is shown. The snare instrument 10 includesan elongate flexible tubular sheath 12 having a proximal end 14 and adistal end 16, a flexible shaft 18 having a proximal end 20 and a distalend 22 extending through and axially movable relative to the sheath 12,a snare 24 coupled to or formed at the distal end 22 of the shaft 18,preferably adjacent the distal end 16 of the sheath 12, and first andsecond handle assemblies 26, 28, respectively, for moving the shaft 18relative to the sheath 12.

The shaft 18 is preferably a high strength, straightened (camber-free)stainless steel wire of high elastic limit. The shaft 18 is adapted tobe bent through a tortuous path without permanent deformation. Inaddition, since the shaft 18 is free of camber, it is possible toprecisely rotate the snare 24 by rotating the shaft at any point alongits length.

Referring now to FIGS. 1 through 3, the physician's handle assembly 26,which is the more distal of the two handles, generally includes a body30 and a knob 32 mounted in the body 30 on bearings 33 a, 33 b in amanner which permits the knob 32 to rotate coaxially relative to thebody. The body 30 includes a central bore 34 with one or more apertures35, a threaded distal end 36, and a threaded proximal end 38. The sheath12 of the snare instrument 10 is connected to the threaded distal end 36of the body 32, e.g., by means of a flare-nut connection 42. Preferably,a stiffening sleeve 44 is provided over the sheath 12 at the connection42. The knob 32 includes a non-circular bore 40, e.g., having thecross-sectional shape of a square. The knob 32 (for reasons discussedbelow) is preferably at least as long as the distance of movementrequired to open and close the snare 24; i.e., the length of the snarewhen compressed in the sheath 12. The apertures 35 provide access to theknob 32, so that the knob 32 can be rotated relative to the body 30,e.g., by a physician.

A portion of the shaft 18 extending through the bore 40 of the knob 32is provided with a key 46; that is, a spline element fixed on and aboutthe shaft 18 or, alternatively, rigidly and fixedly interposed betweentwo portions of the shaft. The key 46 preferably has a rectangular shapebut may have another non-circular shape. The key 46 is slidably axiallymovable within the bore 40. Therefore, the shaft 12 may be moved axiallythrough the bore 40 (and that is why the length of the knob 32 ispreferably at least as long as the distance of movement required to openand close the snare). However, when the knob 32 is rotated relative tothe body 30, the key 46 within the bore 40 is rotated and, consequently,the shaft 18 and snare 24 are rotated relative to the sheath 12.

The distal handle assembly 28 is preferably positioned approximately 210cm from the distal end 16 of the sheath 12 for a snare instrument 10designed to be inserted into a 200 cm endoscope. Thus, the physician cangrip the body 30 in a manner which permits rotating the knob 32 relativeto the body, and hence the snare 24 relative to the sheath 12, whileusing the body 30 as a grip to axially position the snare instrument 10within the working channel of an endoscope.

The shaft 18 extends out of the proximal end 38 of the body 30 to theproximal handle assembly 28, or assistant handle. The proximal handleassembly 28 preferably includes a stationary member 50 and a spoolmember 52 slidable relative to the stationary member. The stationarymember 50 includes a longitudinal throughbore 56 which the proximal end20 of the shaft 18 extends, a transverse slot 58, a proximal thumb ring60, and a distal threaded connector 62. The proximal end of the shaft 18is preferably provided with a conductive stiffening sleeve 64, and acylindrical conductive bearing 66 is coupled about the proximal end ofthe stiffening sleeve 64. The spool member 62 includes a cross bar 68which extends through the transverse slot 58 to secure the spool member52 on the stationary member 50. In addition, the spool member 62preferably includes a cautery plug 70. The conductive bearing 66 extendsthrough the cross bar 68 and a collar 74 secures the bearing 66 in thecross bar 68 in a manner which permits the conductive bearing to freelyrotate within the cross bar 68. A spring 72 extends between the cauteryplug 70 and the conductive bearing 66, and provides a contact betweenthe plug 70 and the bearing 66 regardless of the rotational position ofthe bearing 66. Movement of the spool member 52 relative to thestationary member 50 causes the snare 24 to extend from and retract intothe distal end 16 of the sheath 12.

Referring to FIGS. 1 and 4, an electrically insulative extension sheath80 extends over the shaft 18 between the proximal end 38 of the body 30and the distal end 62 of the stationary member 50, coupled, e.g., viaflare-nut connections 82, 84. Thus, there is a continuous outerconnection joining, yet spacing apart, the distal handle assembly 26 andthe proximal handle assembly 28. A stiffening sleeve 86 is preferablyprovided over the extension sheath 80 at the proximal end 38 of the body30, and another stiffening sleeve 88 is preferably provided over theextension sheath 80 at the distal end 62 of the stationary member 50.

In use, the physician introduces the snare instrument 10 into theendoscope (not shown), typically by means of a port in the endoscopehandle which communicates with the working channel of the endoscope.Then, the physician gives the proximal assistant's handle 28 to theassistant. The physician then grips the body 30 of the distalphysician's handle 26 of the snare instrument and uses it to positionthe distal end 16 of the sheath 12 adjacent to the polyp to be excised.The physician then instructs the assistant to extend the snare, which isperformed by moving the spool member 52 relative to the stationarymember 50. The physician then uses the distal handle 26 tosimultaneously axially position and rotate the snare over the polyp.Then, the physician instructs the assistant to close the snare and severthe polyp, using cautery if desired. In this manner, the physiciancontrols the means of positioning the snare onto the polyp, and theassistant controls the opening and closing of the snare and thecauterization.

In the first embodiment, as discussed above, it will be appreciated thatthe knob 32 is preferably at least as long as the distance of movementneeded to open and close the snare 24. However, turning now to FIGS.5-7, according to a second embodiment of a snare instrument 110, the key146 on the shaft 118 is made sufficiently small in diameter such that itcan pass partly into the bearings 190, 191 on the body 130 (whichsupport the knob 132) and proximal and distal ends 136, 138 of the body130, or even into the sheath 112 and extension sheath 180, and theirrespective stiffening sleeves. Accordingly, the knob 132 is providedwith a hollow knob shaft 192 having a non-circular bore 140 whichrotatably engages the key 146 on the instrument shaft 118. The knobshaft 192 extends beyond the proximal and distal ends of the knob 132.The knob shaft 192 extends into bearings 190, 191 of the body 130 whichallows the knob 132 and knob shaft 192 to spin within the body 130. Theknob shaft 192 may optionally extend through the proximal and distalends 136, 138 of the body 130, into the sheath (on the distal end) andinto the extension sheath (on the proximal end). In this manner, it ispossible to achieve a large range of axial motion (e.g., 3.5 inches)while having a knob 132 of much shorter dimension (e.g., 1.25 inches).It should be noted that if the key 146 has a substantial length (e.g.,0.75 inch), the body 130 and knob 132 can be made even shorter, since itis necessary for only a portion of the key 146 to be engaged with thenon-circular bore 140 of the knob shaft 192 at any time.

In addition, while the first embodiment describes a shaft 18 that ismonolithic and continuous from the snare 24 to the proximal handleassembly 28, the shaft may alternatively be a composite structure.Specifically, referring to FIGS. 8 and 9, according to a thirdembodiment of the invention, the straightened, torsionally-stiff,camber-free section of the shaft 218 need only extend from the snare tothe knob 232. A swivel joint 290 may be interposed on the shaft 218between the knob 232 and the proximal handle assembly, and join theshaft 218 to a flexible or stiff proximal shaft extension 292 whichextends to the proximal handle assembly. The proximal end 294 of theshaft 218 is preferably formed into an enlarged section, i.e., a head296, or a separate, enlarged head may be attached to the proximal end ofthe shaft. A swivel tube 298, preferably made of a malleable alloy, suchas brass or stainless steel, is provided over the head 296. A distal end299 of the swivel tube 298 is swaged or crimped to form a loose fit onthe shaft 218, while being small enough to retain the head 296. Theswivel tube 298 is placed onto the shaft 218 such that the head 296 istrapped inside the non-crimped portion 300 of the swivel tube 298. Theextension shaft 292 is pushed into the proximal open end 304 of theswivel tube 298, and the swivel tube 298 is firmly crimped onto theextension shaft 292. The extension shaft 292 is preferably made ofeither a flexible cable, for example, a 1×7 stranded stainless steelcable preferably of 0.032 inch diameter, or a solid wire of a springymaterial such as stainless steel, for example, a 0.020 inch diameter 304stainless steel spring-temper wire. The extension shaft 292 extendsproximally from the swivel tube 298 to the spool so that is transmitsreciprocating longitudinal motion of the spool through the swivel tube298 to the shaft 218.

This variation in construction of the extension shaft 292 is allowedbecause the purpose of the extension of the shaft 218 is merely totransmit the reciprocating axial motion imparted by the proximal handle;thus, if there exists a freely rotational joint between distal shaft 218and the extension shaft 292, there is no requirement for the extensionshaft to be straight, torsionally-stiff, or camber-free.

Turning now to FIG. 10, according to a fourth embodiment of theinvention, the distal handle assembly 326 includes a mount 350 capableof firmly coupling the distal handle assembly 326 to a port in anendoscope handle (not shown), for example, by interference fit. In apreferred configuration, the mount 350 includes a coupling fitting 352which is couplable to the port of the endoscope, and a connector 354which is slidably movable, yet capable of being secured in a position,relative to the coupling fitting 352. The connector 354 has a proximalend 356 which is threadably coupled to the distal end 336 of the body330.

The coupling fitting 352 includes a cylindrical block 358 having anaxial bore 360, and a tubular nosepiece 362 secured in the axial bore360. The connector 354 includes a stepped bore 364 having a relativelylarge central portion 366, and relatively smaller proximal and distalportions 368, 370. The central portion 366 of the stepped bore 364 issized to permit relative axial movement over the block 358. The distalportion 370 of the stepped bore 364 is sufficiently large to permitaxial movement of the connector 354 over the nosepiece 362. A lockingscrew 372 extends radially into the central portion 366 of the steppedbore 364 of the connector 354 such that the screw 372 may be rotated totighten against the block 358 to lock the connector 354 axially relativeto the block. The proximal end 314 of the sheath 312 extends through thenosepiece 362 and block 358 and is fixedly coupled in the proximalportion 368 of the stepped bore 364. Other aspects of the fourthembodiment are substantially as described above with respect to thefirst embodiment.

In use, the snare instrument is inserted through a port of an endoscopeuntil the nosepiece 362 of the snare instrument is stably inserted inthe port. The distal end of the sheath of the snare instrument may thenbe adjustably fixed relative the distal end of the endoscope byadjusting the connector 354 (and hence the handle 326, shaft 318, andsheath 312) over the block 358. When the sheath is correctly positioned,screw 372 may be set. The distal handle 326 may then be operated, asdescribed with respect to the first embodiment, to rotate the shaft 318and snare relative to the sheath 312. Likewise, a proximal handleassembly, as described with respect to the first embodiment, may then bemanipulated to longitudinally move the shaft 318 to open and close thesnare (the sheath having been previously set in position). With theabove described embodiment, it may be possible for the physician tooperate without an assistant as the axial placement of the snareinstrument is established and set prior to rotation and activation ofthe snare loop.

Referring now to FIG. 11, according to a fifth embodiment of theinvention, a single handle assembly 427 capable of being fixed relativeto an endoscope handle is provided. The handle assembly 427 of the snareinstrument includes all of the controls previously provided in theproximal and distal handle assemblies, and is substantially similar tothe distal handle assembly 326, described above, with the additionalincorporation of the snare opening and closing functions. To thateffect, a sliding spool assembly 428 for longitudinally moving the shaft418 relative to the sheath 412 may be substantially rigidly fixed to theproximal end 438 of the body 430. For example, a distal end 462 of astationary member 450 of the spool assembly 428 may be threadably matedwith the proximal end 438 of the body 430. The spool assembly ispreferably otherwise substantially as described with respect to proximalhandle assembly 28 of the first embodiment of the invention.

The resulting device is fixedly couplable relative to an endoscopichandle and provides to the physician the following controls: a means forcontrollably advancing, retracting, and setting the sheath of the snareinstrument relative to the distal end of the endoscope; a means foradvancing (opening) and retracting (closing) the snare relative to thedistal end of the sheath; and a means for steering (rotating) the snareto position the snare over a polyp. Since the physician has direct andimmediate control of the entire instrument, the snare instrumentobviates the need for an assistant during the procedure, and improvesthe speed and efficiency of the procedure.

There have been described and illustrated herein several embodiments ofa surgical snare instrument. While particular embodiments of theinvention have been described, it is not intended that the invention belimited thereto, as it is intended that the invention be as broad inscope as the art will allow and that the specification be read likewise.Thus, while the use of particular monolithic and composite shafts havebeen disclosed with respect to a snare instrument, it will beappreciated that other flexible shafts may also be provided. Also, whilethe cautery connector has been shown on the proximal handle, it will beappreciated that the cautery connection may be provided in thephysician's handle, or elsewhere along the length of the device,provided that the cautery connection will not interfere with the axiallongitudinal and rotating motions of the shaft. Furthermore, whileparticular shapes and configurations have been described with respect tothe proximal and distal handles, it will be appreciated that othershapes and configurations may be provided therefor. As such, it willalso be appreciated that other configurations which provide a grippinghandle for the sheath, means for rotating the shaft, and means forlongitudinally moving the shaft may be used. For example, a control knobwhich rotates about an axis perpendicular to the axis of the shaft via aright-angle drive (using two meshing bevel gears) may be used to rotatethe shaft. The gears may be configured to permit step-up or step-downrotation, for example, such that rotation of the shaft rotates the shafttwice as much or one-half as much. In addition, levers, gears, frictionwheels, pulleys, links, etc., may be used to longitudinally move theshaft within the sheath, and the snare relative to the distal end of thesheath. Moreover, while a particular nosepiece has been described foruse in the fourth and fifth embodiment, it will be appreciated thatother nosepieces enabling stable coupling of the snare handle to anendoscope handle may be used. For example, a threaded connector capableof threading into or over a port on the endoscope handle may be used.Also, in the fourth and fifth embodiment, the mount and the body may beintegrally formed or molded, and in the fifth embodiment, the body andthe proximal sliding spool assembly may be integrally formed or molded.In addition, it will be appreciated that aspects of the variousembodiments may be combined. For example, but not by way of limitation,the key of the second embodiment or the swivel joint of the thirdembodiment may be used in either of the fourth and fifth embodiments.Furthermore, the described handle assemblies may be used with othersurgical instruments where both axial and rotational movement of acontrol member relative to a tubular member is required. For example,the handle may be used in laparoscopic and endoscopic instruments,generally, which include an end effector other than a snare loop. Forexample, and not by way of limitation, end effectors such as baskets andforceps may be used with the handle. It will therefore be appreciated bythose skilled in the art that yet other modifications could be made tothe provided invention without deviating from its spirit and scope asclaimed.

1. A medical device, comprising: a tubular member; a shaft disposedwithin the tubular member; an end effector coupled to the shaft; a firsthandle coupled to the shaft; a second handle coupled to the shaft; and atubular sheath extension disposed between and longitudinally separatingthe first handle from the second handle.
 2. The medical device of claim1, wherein the end effector includes a snare.
 3. The medical device ofclaim 1, wherein the first handle includes a body and a knob, andwherein rotation of the knob results in rotation of the shaft.
 4. Themedical device of claim 3, wherein the knob defines a bore and whereinthe shaft extends through the bore.
 5. The medical device of claim 4,wherein the bore has a non-circular cross section.
 6. The medical deviceof claim 5, wherein the shaft further comprises a key portion providedwith a non-circular cross section engageable with the non-circular crosssection of the bore.
 7. The medical device of claim 1, furthercomprising mounting means for mounting the first handle to an endoscopesuch that the shaft extends through a working channel of the endoscope.8. The medical device of claim 7, wherein the mounting means is adaptedto adjustably fix a distal end of the tubular member relative to adistal end of the endoscope.
 9. The medical device of claim 1, furthercomprising means for providing a cautery current to the shaft.
 10. Themedical device of claim 1, wherein the second handle further comprises astationary member and a spool member slidable relative to the stationarymember, and wherein sliding the spool member results in longitudinalmovement of the shaft.
 11. The medical device of claim 10, wherein thefirst handle is located distal of the second handle.
 12. A medicaldevice, comprising: a tubular member; a shaft disposed within thetubular member; an end effector coupled to the shaft; means for rotatingthe shaft; means for longitudinally shifting the position of the shaftrelative to the sheath; and a tubular sheath extension disposed betweenand longitudinally separating the means for rotating the shaft from themeans for longitudinally shifting the position of the shaft relative tothe sheath.
 13. The medical device of claim 12, wherein the end effectorincludes a snare.
 14. The medical device of claim 12, wherein the meansfor rotating the shaft includes a first handle having a body and a knob,and wherein rotation of the knob results in rotation of the shaft. 15.The medical device of claim 14, wherein the knob defines a bore andwherein the shaft extends through the bore.
 16. The medical device ofclaim 15, wherein the bore has a non-circular cross section.
 17. Themedical device of claim 16, wherein the shaft further comprises a keyportion provided with a non-circular cross section engagable with thenon-circular cross section of the bore.
 18. The medical device of claim12, further comprising mounting means for mounting the means forrotating the shaft to an endoscope such that the shaft extends through aworking channel of the endoscope.
 19. The medical device of claim 18,wherein the mounting means is adapted to adjustably fix a distal end ofthe tubular member relative to a distal end of the endoscope.
 20. Themedical device of claim 12, further comprising means for providing acautery current to the shaft.
 21. The medical device of claim 12,wherein the means for longitudinally shifting the position of the shaftrelative to the sheath further comprises a stationary member and a spoolmember slidable relative to the stationary member, and wherein slidingthe spool member results in longitudinal movement of the shaft.
 22. Themedical device of claim 21, wherein the means for rotating the shaft islocated distal of the means for longitudinally shifting the position ofthe shaft relative to the sheath.
 23. A medical device, comprising: asheath; a shaft slidably disposed within the sheath; a snare coupled tothe shaft; a control member coupled to the shaft for controlling theposition of the shaft relative to the sheath, the control memberincluding a first handle, a second handle, and a tubular sheathextension disposed therebetween.